Visceral sarcomas frequently develop multi-focal involvement of the peritoneal cavity. Similarly patients with retroperitoneal sarcomas can also develop multi-focal sarcoma of the peritoneal cavity. There's no effective treatment strategy for either of these problems. In a prior study (Z01 CM 0693-02 RO, Study of Surgery and Photodynamic Therapy for Intraperitoneal Malignancies), we develop the technique and defined the maximum tolerated dose of photodynamic therapy that could be delivered to the peritoneal surface. As a natural extension of that prior study, we are moving forward with this Phase II Study of Resection and Intraoperative Photodynamic Therapy for Intraperitoneal Sarcomatosis or Recurrent Retroperitoneal Sarcomas. Patients receive the dihematoporphyrin ethers photosensitizer 2.5 mg/kg 48 hours prior to a surgical procedure which involves surgical removal of tumor and intraoperative light delivery for photodynamic effect to the entire peritoneal surface.